The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a handheld wireless network device (device) 100 may comprise an antenna 102, an antenna sharing module 103, a first communication module 104, and a second communication module 106. The first and second communication modules 104, 106 may communicate using different wireless communication standards (standards). Accordingly, the device 100 is said to communicate using collocated communication modules that use different communication standards.
For example only, the first communication module 104 may communicate using a Fourth Generation (4G) standard or a Bluetooth® (BT) standard. The 4G standard may include Worldwide Interoperability for Microwave Access (WiMAX), Third Generation Partnership Project (3GPP) Long Term Evolution (LTE), or Ultra Mobile Band (UMB) standard. Throughout the disclosure, the WiMAX standard is used as an example only. However, the discussion is applicable to other 4G standards and the BT standard.
The second communication module 106 may communicate using one of the I.E.E.E. 802.11 communication standards. For example only, the second communication module 106 may communicate using a wireless fidelity (WiFi) standard that uses the I.E.E.E. 802.11 specification. Alternatively, the second communication module 106 may communicate using BT with an Alternative Medium access controller (MAC) and Physical layer (PHY) (i.e., BT-AMP) technology. The BT-AMP technology enables BT to support data rates of up to 24 Megabits per second (Mbps) and increases range by using other wireless radio technologies, such as the I.E.E.E. 802.11, as transport medium.
The first communication module 104 using one of the 4G standards (e.g., the WiMAX standard) typically communicates via 2.5 GHz and 2.3 GHz frequency bands. The second communication module 106 typically communicates via the Industrial, Scientific, and Medical (ISM) frequency band of 2.4 GHz. The first and second communication modules 104, 106 may share the antenna 102 via the antenna sharing module 103. Although the antenna 102 is shown as a single antenna, the device 100 may comprise multiple antennas that may be shared by the first and second communication modules 104, 106. Accordingly, data received by the first communication module 104 may occasionally interfere with the data transmitted by the second communication module 106, and vice versa.
For example, data received by the first communication module 104 from a WiMAX base station (BS) (not shown) may interfere with data transmitted by the second communication module 106 to a remote WiFi device (not shown). The remote WiFi device may include an access point (AP) or a client station. The interference may cause the WiMAX BS to drop the data rate of transmission. Dropping the data rate may increase the duration of the transmitted packets. Increasing the duration of the transmitted packets may, in turn, increase the interference. If the interference exceeds a predetermined threshold, the device 100 may be disconnected from the WiMAX BS.
Additionally, data received by the second communication module 106 from the remote WiFi device may interfere with data transmitted by the first communication module 104 to the WiMAX BS. The interference may cause the remote WiFi device to drop the data rate of transmission. Dropping the data rate may increase the duration of the transmitted packets. Increasing the duration of the transmitted packets may, in turn, increase the interference. If the interference exceeds a predetermined threshold, the device 100 may be disconnected from the remote WiFi device.
Referring now to FIG. 2, for example only, the interference between WiMAX and WiFi communications of the device 100 is discussed in detail. The device 100 transmits and receives WiMAX frames using the first communication module 104. Each WiMAX frame comprises a downlink (DL) sub-frame that the device 100 receives and an uplink (UL) sub-frame that the device 100 transmits. Typically, the duration of the WiMAX frame is approximately 5 ms, where the duration of the DL sub-frame is approximately 3.5 ms, and the duration of the UL sub-frame is approximately 1.5 ms.
Additionally, the device 100 also receives and transmits 802.11 packets using the second communication module 106. Typically, when the device 100 receives an 802.11 packet, the second communication module 106 transmits an acknowledgement (ACK) to the remote WiFi device indicating that the 802.11 packet is received by the device 100. If the 802.11 packet is not received by the device 100, the second communication module 106 does not transmit the ACK to the remote WiFi device. When the remote WiFi device does not receive the ACK, the remote WiFi device lowers the data rate and retransmits the 802.11 packet.
If the remote WiFi device again does not receive the ACK from the device 100, the remote WiFi device again lowers the data rate and retransmits the 802.11 packet. The remote WiFi device continues to lower the data rate until the device 100 receives the 802.11 packet as indicated by the ACK received from the device 100. If the ACK is not received after lowering the data rate below a predetermined threshold, the remote WiFi device drops the link to the device.
Occasionally, although the device 100 receives the packet while the device 100 is receiving the WiMAX DL sub-frame, the device 100 may not transmit the ACK to the remote WiFi device for various reasons. For example, the device 100 may not transmit the ACK because the device 100 is configured (e.g., by an arbiter) to not transmit data using the second communication module 106 when the device 100 is receiving WiMAX data. When the remote WiFi device does not receive the ACK, however, the remote WiFi device presumes that the device 100 did not receive the 802.11 packet. Accordingly, the remote WiFi device lowers the data rate, increases the packet duration, and retransmits the 802.11 packet.
If the device 100 is still receiving WiMAX data, the device 100 again may not transmit the ACK to the remote WiFi device. The remote WiFi device again lowers the data rate and retransmits the 802.11 packet. By now, the device 100 may be transmitting the WiMAX UL sub-frame instead of receiving the WiMAX DL sub-frame. Depending on the design of a radio-frequency (RF) front-end of the device 100 (not shown), the second communication module 106 may not receive the 802.11 packet when the first communication module 104 is transmitting data. Accordingly, the remote WiFi device may drop the link to the device 100 instead of lowering the data rate and retransmitting the 802.11 packet. Thus, the interference between the WiMAX and WiFi communications may adversely affect the performance of the device 100.